Image forming method and image forming apparatus

Abstract

To provide an image forming method with which an image with high design properties can be formed with photoluminescent toner without causing filming and poor cleaning on an electrophotographic photoreceptor.SOLUTION: An image forming method includes the steps of: preparing an image forming apparatus having a photosensitive layer; forming an electrostatic latent image on a surface of the photosensitive layer; and developing the electrostatic latent image with a toner for electrostatic charge image development including a photoluminescent pigment to form an image. The photosensitive layer includes a charge transport material having a structure represented by a specific structure.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an image forming method and an image forming apparatus.

Background Art

[0002] In recent years, in the field of commercial printing, it has been required to provide high-quality electrophotographic prints at a higher speed. For image forming apparatuses for forming such prints, durability and the like are also required (for example, Patent Document 1, Patent Document 2). Therefore, in recent years, attempts have been made to form a photocurable protective layer on the surface of the electrophotographic photoreceptor of an image forming apparatus.

[0003] On the other hand, in recent years, higher design images have been required, and also in the above electrophotographic method, attempts have been made to form an image having a metallic luster by using an electrostatic charge image developing toner containing a glitter pigment (hereinafter also referred to as "glitter toner").

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a general electrophotographic photoreceptor, after transferring toner for developing an electrostatic charge image (hereinafter also simply referred to as "toner") onto a recording medium, the toner remaining on the surface of the photosensitive layer is removed by a cleaning blade. And at this time, even if the toner is firmly adhered to the surface of the electrophotographic photoreceptor, the cleaning blade can remove the toner and the like by scraping off an extremely minute region on the surface of the photosensitive layer. However, the electrophotographic photoreceptor having the above-described photocurable protective layer has a very high surface hardness. Therefore, when toner or the like adheres firmly to the surface of the photosensitive layer, the surface (toner) of the photosensitive layer cannot be scraped off by the cleaning blade, and the adhered toner may cause image defects. Also, a state in which toner adheres thinly to the surface of the photosensitive layer (hereinafter also referred to as "filming") was likely to occur.

[0006] On the other hand, a luminous toner is less likely to adhere uniformly to the surface of the photosensitive layer than a general toner. Also, a luminous toner is used for a portion where it is desired to enhance the design property or a portion that is particularly desired to be conspicuous in an image. Therefore, in an image using a luminous toner, variations in the adhesion amount are likely to be noticeable, and it is required to make the luminous toner adhere to the recording medium more uniformly.

[0007] The present invention has been made in view of such problems. Specifically, an object of the present invention is to provide an image forming method capable of forming an image with high design property using a luminous toner without causing filming or cleaning failure in an electrophotographic photoreceptor, and an image forming apparatus used therefor.

Means for Solving the Problems

[0008] The present invention provides the following image forming method. A step of preparing an image forming apparatus having a photosensitive layer, a step of forming an electrostatic latent image on the surface of the photosensitive layer, and a step of developing the electrostatic latent image with a toner for developing an electrostatic charge image containing a luminous pigment to form an image, wherein the photosensitive layer contains a charge transporting material having a structure represented by the following general formula (1).

Chemical formula

[0009] The present invention also provides the following image forming apparatus. An image forming apparatus having an electrophotographic photoreceptor having a photosensitive layer, a charging means for charging the surface of the electrophotographic photoreceptor, an exposure means for exposing the charged surface of the electrophotographic photoreceptor to form an electrostatic latent image, a developing means for developing the electrostatic latent image with toner for electrostatic charge image development to form a visible image, a transfer means for transferring the visible image to a recording medium, and a fixing means for fixing the transferred image on the recording medium, wherein the photosensitive layer contains a charge transport material having a structure represented by the following general formula (1), and the toner for electrostatic charge image development contains a phosphorescent pigment. [Chemical formula] (In general formula (1), R 1 and R 2 each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, k and l each independently represent an integer of 1 to 5, X represents a single bond or an alkyl chain, and Y represents a structure derived from a reactive group) [Advantages of the Invention]

[0010] According to the image forming method and the image forming apparatus of the present invention, filming hardly occurs on the electrophotographic photoreceptor, and further, poor cleaning hardly occurs. In addition, an image with high design quality can be formed by the phosphorescent toner. [Brief Description of the Drawings]

[0011]

Figure 1

Figure 2

[0012] Hereinafter, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiment.

[0013] The image forming method of the present invention is a method for forming a highly artistic image using an image forming apparatus having a specific photosensitive layer and a fluorescent toner.

[0014] As described above, in a conventional general electrophotographic image forming apparatus, durability of the electrophotographic photoreceptor has been emphasized, and attempts have been made to form a protective layer or the like having a three-dimensional crosslinked structure on its surface. However, when such a protective layer is formed, filming or poor cleaning may occur, and an image of desired quality may not be obtained.

[0015] In addition, when a fluorescent toner is set in an electrophotographic image forming apparatus and an image is formed, there has been a problem that gloss unevenness is likely to be conspicuous in the obtained image. Therefore, there has also been a demand for providing a method for forming an image with less gloss unevenness using a fluorescent toner.

[0016] On the other hand, in the image forming method of the present invention, a step of preparing an image forming apparatus having a photosensitive layer (image forming apparatus preparation step), a step of forming an electrostatic latent image on the surface of the photosensitive layer (electrostatic latent image forming step), and a step of developing the electrostatic latent image with an electrostatic charge image developing toner containing a fluorescent pigment to form an image (developing step) are performed.

[0017] The photosensitive layer of the image forming apparatus prepared in the above-described image forming apparatus preparation step contains a charge transport material having a specific structure. Since the charge transport material includes a structure in which a plurality of charge transport material precursors (monomers) are polymerized, the photosensitive layer has appropriate hardness and is difficult to wear. That is, sufficient hardness can be achieved without forming a protective layer on the photosensitive layer. On the other hand, since the toner contains a phosphorescent pigment, appropriate friction is likely to occur between the photosensitive layer and the toner (phosphorescent pigment) during cleaning. Therefore, the surface of the photosensitive layer is moderately scraped off, and filming and cleaning defects are less likely to occur in the photosensitive layer.

[0018] Further, in the above charge transport material, the portion contributing to charge transport and the portion contributing to polymerization are moderately separated within the molecule. This is preferable in terms of ensuring charge transfer performance by having a charge transport skeleton and expressing strength by having a crosslinked structure. Therefore, the charge transport property of the photosensitive layer becomes very good, and it is easy to uniformly adhere toner to the surface of the photosensitive layer. That is, even if the shape of the toner is not spherical, it is easy to uniformly adhere the toner to the surface of the photosensitive layer. Therefore, it is possible to uniformly transfer the toner containing the phosphorescent pigment, and an image with high design quality can be obtained.

[0019] Hereinafter, each step of the image forming method of the present invention will be described in detail. However, the image forming method of the present invention may include steps other than the above as long as the object and effect of the present invention are not impaired.

[0020] 1. Image forming apparatus preparation step In the image forming apparatus preparation step, an image forming apparatus having a photosensitive layer including a specific structure is prepared. An example of the image forming apparatus 1 (the image forming apparatus 1 of the present invention) prepared in this step is shown in FIG. 1. The image forming apparatus 1 includes an image reading unit 110, an image processing unit 30, an image forming unit 40, a paper conveyance unit 50, and a fixing unit 60. The image forming apparatus 1 only needs to have an electrophotographic photosensitive member (hereinafter, also simply referred to as "photosensitive member") 413 of the image forming unit 40 having a specific photosensitive layer 3, and other than the photosensitive layer 3, it can be the same as a normal image forming apparatus. Further, in the image forming apparatus 1, a fluorescent toner containing a fluorescent pigment is used as the toner. Therefore, the photosensitive member 413 and the fluorescent toner will be described in detail below.

[0021] 1-1. Photosensitive Member FIG. 2 schematically shows an example of the layer structure of the photosensitive member 413 of the image forming apparatus 1. The photosensitive member 413 only needs to have at least a conductive support 10 and a photosensitive layer 3 disposed on the conductive support 10, but if necessary, an intermediate layer (not shown) having a barrier function and an adhesion function may be further provided between the conductive support 10 and the photosensitive layer 3. Also, within a range that does not impair the object and effect of the present invention, a protective layer (not shown) for protecting the surface of the photosensitive member 413 may be provided on the photosensitive layer 3. However, as described above, since the photosensitive layer 3 has sufficient behavior, the protective layer may not be provided, and particularly from the viewpoint of enhancing filming resistance and cleaning properties, it is preferable that there is no protective layer. Hereinafter, each component of the photosensitive member 413 will be described.

[0022] (1) Conductive Support The conductive support 10 is a member for supporting the photosensitive layer 3 and is composed of a conductive member. Examples of the type of the conductive support 10 include a metal drum, a metal sheet, a plastic film laminated with a metal foil, a plastic film vapor-deposited with a conductive substance, and a metal member, a plastic film, paper, etc. coated with a paint containing a conductive substance. The type of the metal is not particularly limited as long as it has conductivity, and examples thereof include aluminum, copper, chromium, nickel, zinc, and stainless steel. Examples of the conductive substance include the above metals, indium oxide, tin oxide, etc.

[0023] The shape and structure of the conductive support are appropriately selected according to the type and use of the image forming apparatus 1, etc.

[0024] (2) Photosensitive layer The photosensitive layer 3 is a layer for forming an electrostatic latent image of a desired image on its surface by exposure in an image forming apparatus and is a layer containing a charge transport substance having a specific structure. In FIG. 2, the photosensitive layer 3 is shown as a laminate of a charge generation layer 11 containing a charge generating substance and a charge transport layer 12 containing a specific charge transport substance. However, the photosensitive layer 3 may be a single layer containing a charge generating substance and a specific charge transport substance.

[0025] (Charge generation layer) The charge generation layer 11 is a layer disposed on the conductive support 10 and only needs to contain a charge generating substance capable of generating charges, and is usually a layer containing a charge generating substance and a binder resin.

[0026] Examples of the charge generating substance include azo raw materials such as Sudan Red and Dian Blue; quinone pigments such as pyrenequinone and anthraanthrone; quinocyanine pigments; perylene pigments; indigo pigments such as indigo and thioindigo; phthalocyanine pigments, etc. The charge generation layer 11 may contain only one kind of charge generating substance or two or more kinds. Also, the amount of the charge generating substance in the charge generation layer 11 is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass, with respect to 100 parts by mass of the binder resin.

[0027] Examples of the binder resin included in the charge generation layer 11 include polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride-based resin, vinyl acetate-based resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, copolymer resins containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, etc.), poly-vinyl carbazole resin, and the like. The charge generation layer 11 may contain only one type of binder resin or two or more types of binder resins.

[0028] The thickness of the charge generation layer 11 is preferably about 0.01 to 5 μm, more preferably 0.05 to 3 μm.

[0029] The method for forming the charge generation layer 11 is not particularly limited. For example, a coating solution for the charge generation layer in which the charge generating substance and the binder resin are dissolved in a solvent is applied onto the conductive support 10 and solidified, whereby the charge generation layer 11 can be formed.

[0030] The solvent used for the coating solution for the charge generation layer is not particularly limited as long as it can uniformly disperse or dissolve the charge generating substance and the binder resin. Examples thereof include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, 3-methyl-2-butanone, cyclohexanone, diethylamine, or a mixture thereof.

[0031] The method for preparing the coating solution for the charge generation layer is not particularly limited. For example, the charge generating substance and the like may be dispersed by a dispersing machine such as an ultrasonic disperser, a ball mill, a sand grinder, or a homomixer.

[0032] Furthermore, the coating method of the coating liquid for the charge generation layer is appropriately selected according to the composition of the coating liquid for the charge generation layer, and examples thereof include dip coating method and spray coating method. Furthermore, the solidification method of the coating liquid for the charge generation layer is appropriately selected according to the type of solvent, the desired thickness of the charge generation layer, etc. Natural drying, heat drying, etc. may be used.

[0033] (Charge transport layer) The charge transport layer 12 is a layer disposed on the above-mentioned charge generation layer 11 and is a layer containing a charge transport material having a specific structure. The charge transport layer 12 may further contain a binder resin.

[0034] The charge transport material only needs to contain a structure (structural unit) represented by the following general formula (1). Usually, the charge transport material has a structure in which a plurality of structural units represented by the following general formula (1) are connected in series via Y. The charge transport material may contain only one kind of the following structural unit or may contain two or more kinds. In addition, the charge transport material may contain a structure other than the structure represented by the following general formula (1). However, it is preferable that 80% by mass or more of the total amount of the structural units of the charge transport material (polymer) is a structural unit represented by the following general formula (1), and it is more preferable that all are structural units represented by the following formula (1).

[0035] [Chemical formula] Here, in the above general formula (1), R 1 and R 2 each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms. Among these, a methyl group, an n-propyl group, and a methoxy group are preferable, and a methyl group is more preferable. Also, k and l each independently represent an integer of 1 to 5, and 1 to 2 is more preferable. When k or l is 2 or more, a plurality of R 1 or a plurality of R 2 may all be the same group or may be different.

[0036] Furthermore, in the general formula (1) above, X represents a single bond or an alkyl chain. When X is an alkyl chain, the alkyl chain may be linear or branched. Among them, X is preferably a single bond or a linear alkyl chain having 5 or fewer carbon atoms, that is, a structure represented by the following general formula (2).

Chemical formula

[0037] On the other hand, Y represents a structure derived from a reactive group and represents the structure after the reactive group has reacted (polymerized). In this specification, a reactive group refers to a group that can react and polymerize by heating or the like after the application of the coating solution for forming the charge transport layer. Examples of reactive groups include functional groups having an unsaturated carbon double bond. Specific examples include acryloyl group, methacryloyl group, vinylphenyl group, allyl group, vinyl group, vinyl ether group, allyl vinyl ether group, and derivatives thereof. Among these, from the viewpoint of reactivity, a vinyl group, acryloyloxy group, and methacryloyloxy group are more preferable.

[0038] When the charge transport layer 12 contains the charge transport material having the above structure, its hardness becomes moderately high. On the other hand, in the above charge transport material, the polymerized portion (Y) and the charge transport portion (the portion containing the aromatic ring) are moderately separated. Therefore, the charge transport portion functions sufficiently easily, and the charge transport property of the charge transport layer 12 becomes high.

[0039] Here, the amount of the charge transport material is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass, based on 100 parts by mass of the binder resin.

[0040] On the one hand, examples of the binder resin included in the charge transport layer 12 include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, and styrene-methacrylate copolymer resin, etc. The charge transport layer 12 may contain only one kind of binder resin or two or more kinds of binder resins.

[0041] In addition, the charge transport layer 12 may contain an antioxidant or the like as necessary. The type of antioxidant is not particularly limited, and those disclosed in, for example, JP-A-2000-305291 are preferred.

[0042] The thickness of the charge transport layer 12 is preferably 5 to 40 μm, more preferably 10 to 30 μm.

[0043] The charge transport layer 12 can be formed by applying a coating solution for forming a charge transport layer containing a charge transport material precursor having a structure represented by the following general formula (1’), a binder resin or a precursor thereof, and optionally a polymerization initiator, the above-mentioned antioxidant, etc. onto the charge generation layer 11, and polymerizing the charge transport material precursor by heating or active ray irradiation. Note that a solvent may be used as necessary.

[0044]

Chemical formula

[0045] Specific examples of the charge transport material precursor represented by the above general formula (1’) include the following compounds.

Chemical formula

[0046] On one hand, examples of the polymerization initiator include photoinitiators. As the photoinitiator, an alkylphenone-based compound or a phosphine oxide-based compound is preferable. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable.

[0047] In addition, the solvent used in the coating liquid for forming the charge transport layer is not particularly limited as long as it can uniformly disperse or dissolve the above charge transport material precursor and the binder resin. Examples thereof include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, or a mixture thereof.

[0048] Note that the method for preparing the coating liquid for forming the charge transport layer and the coating method are the same as those for the coating liquid for forming the charge generation layer. In addition, the curing of the coating liquid for forming the charge transport layer, that is, the polymerization of the above charge transport material precursor, can be carried out by irradiation with actinic rays, heating, or the like.

[0049] The curing conditions in this case can be appropriately selected according to the type of the charge transport material precursor contained in the coating film, the type of the resin, the type of the solvent, the thickness of the coating film, and the like. For example, when the charge transport material precursor is a component that cures by irradiation with actinic rays, the charge transport layer can be formed by irradiating with actinic rays. As the actinic rays, ultraviolet rays and electron beams are more preferable, and ultraviolet rays are particularly preferable because they are easy to use.

[0050] As the ultraviolet light source, any light source that generates ultraviolet rays can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used. The irradiation conditions vary depending on each lamp, but the irradiation amount of the actinic rays is usually 5 to 500 mJ / cm 2 and preferably 5 to 100 mJ / cm 2It is within the range. The power of the lamp is preferably 0.1 kW to 5 kW, and particularly preferably within the range of 0.5 kW to 3 kW.

[0051] There is no particular limitation on the electron beam irradiation device which is an electron beam source. Generally, an electron beam accelerator for electron beam irradiation is used, and a curtain beam type electron beam accelerator which is relatively inexpensive and can obtain a large output is effectively used. The acceleration voltage during electron beam irradiation is preferably within the range of 100 to 300 kV. The absorbed dose is preferably within the range of 0.5 to 10 Mrad.

[0052] In order to obtain the required irradiation dose of actinic rays, the irradiation time of actinic rays is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of working efficiency.

[0053] On the other hand, when polymerizing the charge transport substance precursor by heating, the heating temperature is preferably 100 to 140 °C, and more preferably 110 to 130 °C. Within this temperature range, the polymerization of the charge transport substance precursor can be sufficiently carried out. Further, the heating time is preferably 50 to 150 minutes, and more preferably 60 to 120 minutes.

[0054] (Intermediate layer) As described above, an intermediate layer may be formed between the conductive support 10 and the photosensitive layer 3. The intermediate layer can be a layer containing a binder resin and inorganic particles.

[0055] Examples of the binder resin contained in the intermediate layer include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin, etc. The intermediate layer may contain only one kind of binder resin, or may contain two or more kinds.

[0056] Examples of the inorganic particles included in the intermediate layer include metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide; and ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide. The intermediate layer may contain only one of these or two or more of them.

[0057] Further, when the intermediate layer contains two or more kinds of metal oxide particles, the metal oxide particles may be in a solid solution state or a fused state. The number average primary particle diameter of the metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less. The number average primary particle diameter of the above metal oxide particles is obtained by photographing the metal oxide particles in the intermediate layer with a scanning electron microscope JEM-7500F (manufactured by JEOL Ltd.) at an acceleration voltage of 80 kV, and from a magnified photograph at 10,000 times, 100 photographic images of metal oxide particles (excluding aggregated particles) randomly captured by a scanner are processed and analyzed with an automatic image processing analyzer LUZEXAP (software version Ver. 1.32, manufactured by Nireco Corporation), and the calculated value.

[0058] The amount of the inorganic particles is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

[0059] The thickness of the intermediate layer is preferably 0.1 to 15 μm, more preferably 0.3 to 10 μm.

[0060] The intermediate layer can be formed by applying and solidifying a coating liquid for forming an intermediate layer containing a binder resin, inorganic particles, and a solvent. Examples of the solvent contained in the coating liquid for forming an intermediate layer include ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, tetrahydrofuran, or a mixture thereof.

[0061] Note that the method for preparing the coating liquid for forming the intermediate layer, the coating method, and the solidification method are the same as those for the coating liquid for forming the charge generation layer, the coating method, and the solidification method.

[0062] 1-2. Glow Toner Next, the glow toner used in the above image forming apparatus will be described. The glow toner is composed of toner base particles containing a glow pigment and an external additive. The glow toner may contain other components as long as the object and effect of the present invention are not impaired. The glow toner may be a one-component developer or a two-component developer. When the glow toner is a two-component developer, in addition to the toner base particles and the external additive (hereinafter, these are also collectively referred to as "toner particles"), carrier particles are further included.

[0063] (1) Toner Base Particles The toner base particles contain at least a binder resin and a glow pigment, and usually further contain a release agent.

[0064] (Binder Resin) The binder resin is a resin having a function of binding the toner particles to the recording medium. The binder resin may contain either an amorphous resin or a crystalline resin, or both. When the binder resin contains an amorphous resin and a crystalline resin, in the obtained toner base particles, the amorphous resin forms a matrix that is a continuous phase, and the crystalline resin forms domains that are isolated and dispersed in the matrix.

[0065] The content of the binder resin is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total amount of the toner base particles. When the amount of the binder resin is within this range, the image formed using the glow toner is likely to be fixed to the recording medium.

[0066] ·Amorphous Resin Examples of the amorphous resin contained in the toner base particles include vinyl resins, polyester resins, urethane resins, urea resins, etc., and among them, vinyl resins and polyester resins are preferred. In this specification, the amorphous resin is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed on the resin.

[0067] When the glass transition temperature in the first heating process in DSC measurement is defined as Tg1 and the glass transition temperature in the second heating process is defined as Tg2, Tg1 of the above amorphous resin is preferably 35 to 80 °C, more preferably 45 to 65 °C. Further, Tg2 of the above amorphous resin is preferably 20 to 70 °C, more preferably 30 to 55 °C.

[0068] The molecular weight of the amorphous resin measured by gel permeation chromatography (GPC) is preferably 10,000 to 100,000 in terms of weight average molecular weight (Mw). This value is in terms of polystyrene conversion.

[0069] The vinyl-based resin is a resin having at least a structure derived from a vinyl-based monomer. Specific examples of the amorphous vinyl-based resin include acrylic resins and styrene-acrylic resins obtained from styrene-based monomers and (meth)acrylate-based monomers, and styrene-acrylic resins are preferred. The content of the styrene-acrylic resin is preferably 70% by mass or more based on the total amount of the binder resin. Hereinafter, the styrene-acrylic resin will be described in detail, but the amorphous resin is not limited thereto.

[0070] Examples of the styrene-based monomer that is a raw material for the vinyl-based resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, and derivatives thereof. The styrene-acrylic resin may contain only one of these or two or more thereof.

[0071] Examples of (meth)acrylate monomers that are raw materials for vinyl resins include acrylate monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate; methacrylate esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, etc. Styrene-acrylic resins may contain only one of these or two or more of them.

[0072] In addition, styrene-acrylic resins may contain a structure derived from a third polymerizable monomer other than the above. Examples of the third polymerizable monomer include acid monomers such as acrylic acid, methacrylic acid, maleic anhydride, vinyl acetic acid; (meth)acrylamide; acrylonitrile; ethylene; propylene; butylene vinyl chloride; N-vinyl pyrrolidone, etc. Furthermore, styrene-acrylic resins may contain a structure derived from a polyfunctional vinyl monomer. Examples of polyfunctional vinyl monomers include diacrylates such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, dimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, trimethylolpropane; trimethacrylates; butadiene, etc. Styrene-acrylic resins may contain only one of these or two or more of them.

[0073] Styrene-acrylic resins can be prepared by polymerizing the above monomers by a known emulsion polymerization method or the like. Known polymerization initiators, chain transfer agents, etc. can be used during the polymerization.

[0074] Furthermore, in order to reduce the mechanical strength of the toner and suppress the embedding of the external additive, it is preferable to use an amorphous polyester resin (hereinafter also simply referred to as "amorphous polyester resin") in combination.

[0075] The amorphous polyester resin is produced by a polycondensation reaction of a polyvalent carboxylic acid (derivative) and a polyhydric alcohol (derivative) as raw materials in the presence of an appropriate catalyst.

[0076] A polyvalent carboxylic acid is a compound containing two or more carboxy groups in one molecule. As polyvalent carboxylic acid derivatives, alkyl esters, acid anhydrides, and acid chlorides of polyvalent carboxylic acids can be used.

[0077] Examples of polyvalent carboxylic acids include dibasic carboxylic acids such as oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, dodecenylsuccinic acid; and polyvalent carboxylic acids with three or more carboxy groups such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

[0078] As the polyvalent carboxylic acid, it is preferable to use an unsaturated aliphatic dicarboxylic acid such as fumaric acid, maleic acid, or mesaconic acid, or its acid anhydride.

[0079] A polyhydric alcohol is a compound containing two or more hydroxyl groups in one molecule. As polyhydric alcohol derivatives, ester compounds of polyhydric alcohols and hydroxycarboxylic acids can be used.

[0080] Examples of polyhydric alcohols include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A; and polyols with three or more hydroxyl groups such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine.

[0081] · Crystalline resin When the toner mother particles contain a crystalline resin, the flexibility of the toner mother particles is likely to increase, and the external additive is likely to adhere to the periphery of the toner mother particles. In this specification, "crystalline" means having a distinct endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). The "distinct endothermic peak" means a peak with a half-width at half maximum of the endothermic peak within 15 °C when measured at a heating rate of 10 °C / min in DSC. It can be said that the higher the crystallinity, the smaller the half-width at half maximum of the endothermic peak.

[0082] Here, the type of the crystalline resin is not particularly limited, but it is preferably contained in a crystalline polyester resin. When the binder resin contains a crystalline polyester resin, the toner mother particles are likely to melt, and the low-temperature fixability becomes good.

[0083] The crystalline polyester resin may be any resin that has a plurality of ester structures and has crystallinity. The binder resin may contain only one type of crystalline polyester resin or may contain two or more types. The above-mentioned crystalline polyester resin is usually obtained by subjecting a polyvalent carboxylic acid and a polyhydric alcohol to a dehydration condensation reaction by a known method.

[0084] The polyvalent carboxylic acid for obtaining the crystalline polyester resin may be any carboxylic acid having two or more valences, and may be a carboxylic acid having three or more valences such as trimellitic acid or pyromellitic acid. However, from the viewpoint of the crystallinity of the crystalline polyester resin, dicarboxylic acids are preferred. Examples of dicarboxylic acids include aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. The crystalline polyester resin may contain only one type of structural unit derived from these polyvalent carboxylic acids or may contain two or more types.

[0085] On the one hand, the polyhydric alcohol for obtaining the crystalline polyester resin may be any alcohol having two or more hydroxyl groups, and may also be a polyhydric alcohol having three or more hydroxyl groups such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. However, from the viewpoint of the crystallinity of the crystalline polyester resin, a dihydric alcohol is preferred. Examples of the dihydric alcohol include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol; diols having an unsaturated double bond such as 2-butene-1,4-diol, 3-hexene-1,6-diol, 4-octene-1,8-diol, and further diols having a sulfonic acid group. The crystalline polyester resin may contain only one kind of structural unit derived from these polyhydric alcohols, or may contain two or more kinds.

[0086] Here, from the viewpoint of sufficiently softening the toner base particles to ensure sufficient low-temperature fixability, the melting point of the crystalline polyester resin is preferably 50°C or higher and 85°C or lower, and more preferably 60°C or higher and 80°C or lower from the viewpoint of improving various properties in a well-balanced manner. The melting point of the crystalline polyester resin can be controlled by the structure of the resin (for example, the type of monomer).

[0087] Also, the weight average molecular weight (Mw) of the crystalline polyester resin is preferably 5000 to 50000, and the number average molecular weight (Mn) is preferably 2000 to 20000. When the weight average molecular weight (Mw) and number average molecular weight (Mn) of the crystalline polyester resin are within the above ranges, the low-temperature fixability is improved.

[0088] The above crystalline polyester resin can be prepared by a known method.

[0089] (Fluorescent pigment) The bright pigment may be any pigment capable of imparting gloss to an image, and examples thereof include metal pigments, pearlescent pigments, etc. More specifically, metal powders such as aluminum, brass, bronze, nickel, stainless steel, zinc, copper, silver, gold, platinum, etc.; coated flaky inorganic crystal substrates such as mica coated with titanium oxide or yellow iron oxide, barium sulfate, layered silicate, silicate of layered aluminum, etc.; single crystal plate-like titanium oxide; basic carbonate; bismuth oxychloride; natural guanine; flaky glass powder; flaky glass powder vapor-deposited with metal, etc., as long as it has brightness, there is no particular limitation. Among them, from the viewpoints of cost, stability, availability, and brightness, metal pigments are preferred, aluminum pigments are more preferred, and metal pigments of aluminum metal alone are particularly preferred.

[0090] The shape of the bright pigment is not particularly limited and may be spherical or the like, but a flat shape is preferred. In this specification, that the bright pigment is flat means that the flatness is greater than 1. The flatness is such that when the maximum length of the bright pigment is the major axis, the maximum length in the direction orthogonal to the major axis is the minor axis, and the minimum length in the direction orthogonal to the major axis is the thickness, the ratio of the minor axis to the thickness is 1.4 or more. The flatness of the bright pigment is preferably greater than 1.4, more preferably 1.4 to 150, and even more preferably 5 to 80. When the flatness of the bright pigment exceeds 1.4, the toner particles also tend to be flat, and the frictional force between the above-mentioned photoreceptor 413 and the bright toner becomes better. The flatness of the bright pigment is specified as follows. The measurement of the major axis and the minor axis is to take a 5000-fold photograph of 100 toners with a scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.), and this photographic image is captured by a scanner. Then, it is performed by image analysis using an image processing and analysis device LUZEX (registered trademark) AP (manufactured by Nireco Corporation). The thickness is specified by observing the cross section with a transmission electron microscope.

[0091] When the bright pigment is flat, its planar shape is not particularly limited and may be any shape such as a disc shape or a flake shape. However, the major axis of the flat bright pigment is preferably from 1 to 150, more preferably from 5 to 80. The major axis of the bright pigment means the maximum diameter of the flat bright pigment. When the major axis of the bright pigment is within the above range, the brightness of the resulting image is likely to be good. The major axis of the bright pigment is measured by the method described above.

[0092] On the other hand, the thickness of the bright pigment is preferably from 0.1 to 10, more preferably from 0.5 to 8. When the thickness of the bright pigment is within the above range, it becomes easier to suppress filming of the above-described photoreceptor 413.

[0093] The content of the bright pigment is preferably from 10 to 90% by mass, more preferably from 20 to 80% by mass, based on the total amount of the toner base particles. When the content of the bright pigment is within the above range, the brightness of the resulting image is likely to be good.

[0094] (Release agent) The toner base particles preferably contain a release agent. As the release agent, various known waxes can be used. Examples of waxes include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax; long-chain hydrocarbon waxes such as paraffin wax and sasol wax, dialkyl ketone waxes such as distearyl ketone; ester waxes such as carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, distearyl maleate; amide waxes such as ethylenediamine behenylamide and tristearylamide trimellitate; are included. The release agent may contain only one of these or may contain two or more of them.

[0095] The amount of the release agent is preferably 0.1 to 30 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the above binder resin.

[0096] (Others) In addition to the above binder resin, bright pigment, and release agent, the toner mother particles may further contain necessary components as required. Examples of other components include colorants other than bright pigments, charge control agents, and the like.

[0097] Examples of the colorant include carbon black, magnetic substances, pigments, dyes, and the like. The toner mother particles may contain one kind of colorant or two or more kinds of colorants. The amount of the colorant is appropriately selected according to the desired color, the type of the colorant, and the like.

[0098] On the other hand, the charge control agent is not particularly limited as long as it is a substance capable of imparting positive or negative charge by triboelectrification, and various known positive charge control agents and negative charge control agents can be used. Examples of the charge control agent include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and metal salts of salicylic acid or metal complexes thereof. The toner mother particles may contain only one kind of charge control agent or two or more kinds of charge control agents. The amount of the charge control agent is preferably 2 to 20 parts by mass based on 100 parts by mass of the total amount of the binder resin.

[0099] (Structure and preparation method of toner mother particles) The structure of the toner mother particles may be a single-layer structure or a multilayer structure such as a core-shell structure including a core and a shell layer covering the surface thereof. The shell layer does not necessarily cover the entire surface of the core, and a part of the core may be exposed. The cross section of the core-shell structure can be confirmed by known observation means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM). Note that the core-shell structure referred to in this specification includes structures with three or more layers.

[0100] In the case of a core-shell structure, the properties such as the glass transition point, melting point, and hardness can be made different between the core and the shell layer, enabling the design of toner base particles according to the purpose. For example, a resin with a relatively high glass transition point may be aggregated and fused on the surface of a core containing a binder resin, a bright pigment, a release agent, etc., and having a relatively low glass transition point to form a shell layer.

[0101] Alternatively, for example, binder resin particles having a three-layer structure may be produced by dividing them into three steps: first-stage polymerization (formation of the inner layer), second-stage polymerization (formation of the intermediate layer), and third-stage polymerization (formation of the outer layer). Here, in each of the polymerization reactions of the first-stage polymerization to the third-stage polymerization, by changing the composition of the polymerizable monomer, binder resin particles having a three-layer structure with different compositions can be produced. Further, for example, in any of the first-stage polymerization to the third-stage polymerization, by performing the synthesis reaction of the binder resin in a state containing a release agent or the like, a release agent can be contained in a desired layer. The bright pigment may be mixed when preparing the above binder resin particles, or may be prepared separately from the above binder resin particles and these may be mixed.

[0102] Here, the toner base particles (and thus the toner particles) are preferably flat, and the flatness is preferably greater than 1.4, more preferably 1.4 to 150, and even more preferably 5 to 80. When the flatness of the toner base particles is within this range, filming is less likely to occur. The flatness of the toner base particles is measured by taking a 5000-fold photograph of 100 toners with a scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.) and importing this photographic image by a scanner. Then, it is performed by image analysis using an image processing and analysis device LUZEX (registered trademark) AP (manufactured by Nireco Corporation).

[0103] On the one hand, the volume average particle diameter of the toner base particles is preferably 3 to 50 μm in terms of the volume-based median diameter (D50). By setting the volume-based median diameter within the above range, the reproducibility of thin lines and high image quality can be achieved, and the fluidity of the bright toner can also be ensured. Here, the volume-based median diameter (D50) of the toner base particles can be measured and calculated, for example, using an apparatus connected to a computer system for data processing with a Multi-Sizer 3 (manufactured by Beckman Coulter, Inc.).

[0104] (2) Exterior additive The exterior additive serves to control the fluidity, chargeability, etc. of the toner particles. The exterior additive only needs to contain at least a lanthanum-doped titanate compound. The exterior additive may further contain other compounds.

[0105] (Lanthanum-doped titanate compound) The lanthanum-doped titanate compound may be any titanate compound doped with lanthanum, and the type of titanate compound is not particularly limited. Examples of the lanthanum-doped titanate compound include lanthanum-doped strontium titanate, lanthanum-doped calcium titanate, and lanthanum-doped barium titanate.

[0106] Also, the lanthanum-doped titanate compound may be surface-modified with a surface shrinkage agent. Examples of the surface modification agent include alkylsilazane compounds such as hexamethyldisilazane, alkylalkoxysilane compounds such as dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, butyltrimethoxysilane, chlorosilane compounds such as dimethyldichlorosilane, trimethylchlorosilane, silicone oil, silicone varnish, etc. These surface modification agents may be one kind or two or more kinds.

[0107] The lanthanum content in the lanthanum-doped titanic acid compound is preferably 3.4 to 14.9% by mass based on the total amount of the lanthanum-doped titanic acid compound. When the lanthanum content is 3.4% by mass or more, it becomes closer to a spindle shape, and the frictional force with the photoreceptor 413 can be appropriately adjusted. On the other hand, by setting the lanthanum content to 14.9% by mass or less, it becomes easier to control the particle size, and the generation of coarse particles and the like can be suppressed.

[0108] Also, from the viewpoint of appropriately adjusting the frictional force with the photosensitive layer and having good fluidity, the average circularity of the lanthanum-doped titanic acid compound is preferably 0.82 to 0.990. The measurement of the average circularity in the lanthanum-doped titanic acid compound is performed by taking a photograph of 100 lanthanum-doped titanic acid compounds at 40,000 times magnification with a scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.) and capturing this photographic image with a scanner. Image analysis is performed by using an image processing and analysis device LUZEX (registered trademark) AP (manufactured by Nireco Corporation).

[0109] After obtaining the equivalent circle diameter perimeter and the perimeter from the analyzed image, the circularity of each external additive (lanthanum-doped titanic acid compound) is obtained according to the following formula, and they are averaged. Formula: Circularity = Equivalent circle diameter perimeter / Perimeter = [2×(Aπ)1 / 2] / PM In the above formula, A represents the projected area of the external additive (lanthanum-doped titanic acid compound), and PM represents the perimeter of the external additive (lanthanum-doped titanic acid compound). When the circularity is 1.0, it is a perfect sphere, and the lower the numerical value, the more uneven the outer circumference and the higher the degree of irregularity.

[0110] The number average primary particle diameter of the lanthanum-doped titanic acid compound is preferably 10 to 100 nm. By setting the number average primary particle diameter of the lanthanum-doped titanic acid compound to 10 nm or more, the function as a charge control agent can be effectively expressed, and by setting it to 100 nm or less, the effect of the present invention can be effectively obtained without excessively increasing the abrasiveness.

[0111] The primary particle size of the lanthanum-doped titanic acid compound is measured as follows. After externally adding (dispersing) an external additive to toner base particles, 100 primary particles of the external additive are observed at a magnification of 40,000 times with a scanning electron microscope JSM-7401F (manufactured by JEOL Ltd.). The longest diameter and the shortest diameter of each particle are measured by image analysis of the primary particles, and the equivalent spherical diameter is measured from the median value. Then, the average of the 100 measured primary particle sizes is defined as the number-average primary particle size.

[0112] In addition, the average adhesion strength of the lanthanum-doped titanic acid compound to the surface of the toner base particles is preferably 50 to 100%. When the average adhesion strength is 50% by mass or more, the lanthanum-doped strontium titanate particles are less likely to desorb from the toner base particles.

[0113] The average adhesion strength of the lanthanum-doped titanic acid compound is calculated by measuring the abundance of titanium atoms before and after subjecting the toner particles to ultrasonic dispersion treatment in an aqueous surfactant solution for 3 minutes as follows. 3 g of toner particles are moistened with 40 g of a 0.2% by mass aqueous solution of polyoxyethyl phenyl ether in a 100 mL plastic cup, and ultrasonic energy is applied for 3 minutes using an ultrasonic homogenizer adjusted so that the value of the ammeter indicating the vibration indication value attached to the main body device shows 60 μA (50 W), thereby performing dispersion treatment by ultrasonic waves. Next, the toner particles are filtered using a filter with a mesh size of 1 μm, washed with 60 mL of pure water, and dried.

[0114] Then, for the dried sample (hereinafter referred to as sample A), the amount of titanium atoms remaining in the dried sample A is measured using a wavelength-dispersive X-ray fluorescence spectrometer XRF-1700 (manufactured by Shimadzu Corporation). As a specific measurement method, 2 g of the dried sample A is pressed into a pellet and measured under the following conditions by qualitative analysis. Note that for the measurement, the Kα peak angle of the element to be measured is determined from the 2θ table and used.

[0115] Spectrometer conditions Slit: Standard Attenuator: None Spectroscopic crystal: LiF Detector: SC Also, for 3 g of toner particles, a sample (hereinafter referred to as sample B) is prepared in the same manner except that the above ultrasonic dispersion is not performed, and the titanium atomic weight of the sample B is also measured. Then, the Ti residual rate is calculated by dividing the value of the Net intensity of the TiKα analysis line of sample A by the value of the Net intensity of the TiKα analysis line of sample B, and this is taken as the average adhesion strength.

[0116] Here, from the viewpoint of suppressing fluctuations in the charge amount under different temperature and humidity environments, the content rate of the lanthanum-doped titanate compound is preferably 0.1 to 1.0% by mass with respect to the total amount of toner particles.

[0117] (Other external additives) As external additives, as long as the effects of the present invention are not inhibited, other external additives can be added for the purpose of improving fluidity and chargeability in addition to the lanthanum-doped titanate compound. Examples of other external additives include inorganic oxide fine particles such as fatty acid metals, silica fine particles, alumina fine particles, and titanium dioxide fine particles.

[0118] (3) Physical properties and manufacturing method of toner particles The size and shape of the toner particles containing the above toner base particles and external additives are not particularly limited as long as the effects and purposes of the present invention are not impaired. Usually, the volume-based median diameter (D50) of the toner particles is preferably 3 μm or more and 80 μm or less, and the average circularity of the toner particles is preferably 0.200 or more and 1.000 or less. The method for measuring the volume-based median diameter (D50) of the toner particles and the method for measuring the average circularity of the toner particles are the same as the method for measuring the volume average particle diameter of the toner base particles and the method for measuring the average circularity of the toner base particles.

[0119] The method for manufacturing toner particles is not particularly limited, and the above-described toner base particles and external additives may be mixed by a known method. For mixing the toner base particles and the external additives, a mechanical mixing device or the like can be used. Examples of the mechanical mixing device include a Henschel mixer, a Nauta mixer, a Turbular mixer, and the like. Among these, it is preferable to perform a mixing process such as increasing the mixing time or increasing the rotational peripheral speed of the stirring blades using a mixing device that can apply a shearing force to the particles to be processed like a Henschel mixer. Further, when using a plurality of types of external additives, all the external additives may be mixed with the toner base particles at once, or may be divided and mixed in a plurality of times according to the external additives.

[0120] Further, when mixing the toner base particles and the external additives, the degree of disintegration and the adhesion strength of the external additives can be controlled by controlling the mixing intensity, that is, the peripheral speed of the stirring blades, the mixing time, or the mixing temperature.

[0121] (4) Two-component developer The two-component developer can be prepared by mixing the above-described toner particles and carrier particles or the like.

[0122] The carrier particles included in the two-component developer may be conventionally known magnetic particles, and examples thereof include particles containing metals such as iron, ferrite, magnetite, and alloys of these metals and metals such as aluminum and lead. The carrier particles may be coated carrier particles having a core material particle made of a magnetic material and a layer of a coating material covering the surface thereof. Further, resin-dispersed carrier particles in which fine powder of a magnetic material is dispersed in a resin may be used. From the viewpoint of suppressing the adhesion of the carrier particles to the photoreceptor, coated carrier particles are preferable.

[0123] The average particle diameter of the carrier particles is preferably 15 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less, in terms of the median diameter based on volume. The median diameter based on volume of the carrier particles can be measured, for example, with a laser diffraction particle size distribution measuring device (HELOS; manufactured by SYMPATEC) equipped with a wet disperser.

[0124] Note that the carrier particles may be appropriately mixed with the toner particles described above. Examples of the mixing device used for such mixing include a Nauta mixer, a W-cone, and a V-type mixer.

[0125] The ratio of toner particles to the total of carrier particles and toner particles in the two-component developer (toner concentration) is preferably 4.0 to 8.0% by mass. When the ratio of toner particles is 4.0 to 8.0% by mass, the charge amount of the toner becomes appropriate, and the image quality after initial and continuous printing becomes better.

[0126] 1-3. Other Configurations of the Image Forming Apparatus Hereinafter, the photosensitive member 413 of the image forming apparatus 1 (the image forming apparatus of the present invention) used in the image forming method of the present invention, and configurations other than the fluorescent toner will be described.

[0127] The image forming unit 40 of the image forming apparatus 1 may have an image forming unit 41L that forms an image using the fluorescent toner described above, but may further include image forming units 41Y, 41M, 41C, and 41K for each color toner of Y (yellow), M (magenta), C (cyan), and K (black). In this case, the image forming unit 41L may be arranged, for example, in front of Y (yellow) or behind K (black). Each color toner can be obtained by changing the fluorescent pigment of the fluorescent toner described above to each color toner. The image forming unit 40 further has an intermediate transfer unit 42 and a secondary transfer unit 43. These correspond to transfer means.

[0128] The image forming unit 41 includes an exposure unit 411, a developing unit 412, the above-described photoreceptor 413, a charging unit 414, and a drum cleaning device 415. The above-described photoreceptor 413 is used, for example, as a negatively charged organic photoreceptor. The charging unit 414 is, for example, a corona charger. The charging unit 414 may be a contact charging unit that contacts the photoreceptor 413 with a contact charging member such as a charging roller, a charging brush, or a charging blade to charge it. The exposure unit 411 includes, for example, a semiconductor laser as a light source and a light deflector (polygon motor) that irradiates the photoreceptor 413 with laser light corresponding to the image to be formed.

[0129] The developing unit 412 shown in FIG. 1 is a developing device using a two-component developing system. The developing unit 412 includes, for example, a developing container that houses a two-component developer, a developing roller (magnetic roller) rotatably disposed at an opening of the developing container, a partition wall that partitions the inside of the developing container so that the two-component developer can communicate, a conveying roller for conveying the two-component developer on the opening side of the developing container toward the developing roller, and a stirring roller for stirring the two-component developer in the developing container. The above-described developing container houses the above-described fluorescent toner or the like as the two-component developer.

[0130] The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422 that presses the intermediate transfer belt 421 against the photoreceptor 413, a plurality of support rollers 423 including a backup roller 423A, and a belt cleaning device 426. The intermediate transfer belt 421 is looped around a plurality of support rollers 423. When at least one driving roller among the plurality of support rollers 423 rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

[0131] The secondary transfer unit 43 includes an endless secondary transfer belt 432 and a plurality of support rollers 431 including a secondary transfer roller 431A. The secondary transfer belt 432 is looped by the secondary transfer roller 431A and the support rollers 431.

[0132] The fixing means 60 includes, for example, a fixing roller 62, an endless heating belt 63 that covers the outer peripheral surface of the fixing roller 62 and heats and melts the toner that constitutes the toner image on the paper S, and a pressure roller 64 that presses the paper S toward the fixing roller 62 and the heating belt 63. The paper S corresponds to a recording medium.

[0133] The image forming apparatus 1 further includes an image reading unit 110, an image processing unit 30, and a paper conveyance unit 50. The image reading unit 110 includes a paper feeding device 111 and a scanner 112. The paper conveyance unit 50 includes a paper feeding unit 51, a paper discharging unit 52, and a conveyance path unit 53. In the three paper feeding tray units 51a to 51c that constitute the paper feeding unit 51, papers S (standard papers, special papers) identified based on basis weight, size, etc. are stored for each preset type. The conveyance path unit 53 includes a plurality of conveyance roller pairs such as a registration roller pair 53a.

[0134] 2. Electrostatic latent image forming process and developing process A method for performing an electrostatic latent image forming process and a developing process using the image forming apparatus 1 prepared in the above image forming apparatus preparation process will be described.

[0135] First, the scanner 112 of the image forming apparatus optically scans and reads the document D on the contact glass. The reflected light from the document D is read by the CCD sensor 112a and becomes input image data. The input image data is subjected to predetermined image processing in the image processing unit 30 and sent to the exposure means 411.

[0136] The photoreceptor 413 rotates at a constant peripheral speed. The charging means 414 uniformly charges the surface of the photoreceptor 413 negatively. In the exposure means 411, the polygon mirror of the polygon motor rotates at high speed, and laser light corresponding to the input image data of each color component is developed along the axial direction of the photoreceptor 413 and irradiated onto the outer peripheral surface of the photoreceptor 413 along the axial direction. Thus, an electrostatic latent image is formed on the surface of the photoreceptor 413 (electrostatic latent image forming process).

[0137] In the developing means 412, toner particles are charged by stirring and transporting the two-component developer in the developing container, and the two-component developer is transported to the developing roller, where a magnetic brush is formed on the surface of the developing roller. The charged toner particles are detached from the magnetic brush and electrostatically adhere to the portion of the electrostatic latent image on the photoreceptor 413. In this way, the electrostatic latent image on the surface of the photoreceptor 413 is visualized, and a toner image (visible image) corresponding to the electrostatic latent image is formed on the surface of the photoreceptor 413 (developing step). In this specification, the "toner image" refers to a state in which toner is aggregated in an image shape.

[0138] Thereafter, the toner image on the surface of the photoreceptor 413 is transferred to the intermediate transfer belt 421 by the intermediate transfer unit 42. The transfer residual toner remaining on the surface of the photoreceptor 413 after the transfer is removed by a drum cleaning device 415 having a drum cleaning blade that is in sliding contact with the surface of the photoreceptor 413.

[0139] When the intermediate transfer belt 421 is pressed against the photoreceptor 413 by the primary transfer roller 422, a primary transfer nip is formed for each photoreceptor 413 by the photoreceptor 413 and the intermediate transfer belt 421. In the primary transfer nip, toner images of each color are sequentially overlapped and transferred to the intermediate transfer belt 421.

[0140] On the other hand, the secondary transfer roller 431A is pressed against the backup roller 423A via the intermediate transfer belt 421 and the secondary transfer belt 432. Thereby, a secondary transfer nip is formed by the intermediate transfer belt 421 and the secondary transfer belt 432. The sheet S passes through the secondary transfer nip. The sheet S is transported to the secondary transfer nip by the sheet transport unit 50. Correction of the inclination of the sheet S and adjustment of the transport timing are performed by a registration roller unit provided with a pair of registration rollers 53a.

[0141] When the paper S is conveyed to the secondary transfer nip, a transfer bias is applied to the secondary transfer roller 431A. By applying this transfer bias, the toner image carried on the intermediate transfer belt 421 is transferred to the paper S. The paper S onto which the toner image has been transferred is conveyed by the secondary transfer belt 432 toward the fixing means 60.

[0142] The fixing means 60 forms a fixing nip portion by the heating belt 63 and the pressure roller 64, and heats and presses the conveyed paper S at the fixing nip portion. In this way, the toner image (transferred image) is fixed to the paper S. The paper S onto which the toner image has been fixed is discharged outside the machine by the discharging portion 52 including the discharging roller 52a.

[0143] Note that the residual transfer toner remaining on the surface of the intermediate transfer belt 421 after secondary transfer is removed by a belt cleaning device 426 having a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 421.

Example

[0144] Hereinafter, specific examples of the present invention will be described together with comparative examples, but the present invention is not limited thereto. In the examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[0145] 1. Production of electrophotographic photoreceptor 1-1. Production of electrophotographic photoreceptor 1 (electrophotographic photoreceptors of Examples 1 and 3 to 11) · Preparation of conductive support A conductive support including a drum-shaped aluminum support was prepared.

[0146] (1) Formation of intermediate layer Binder resin for the intermediate layer: 50 parts by mass of polyamide resin CM8000 (manufactured by Toray Industries, Inc.) was added to 1000 parts by mass of a mixed solvent of ethanol / n - propyl alcohol / tetrahydrofuran (volume ratio: 45 / 20 / 35), and stirred and mixed at 20°C. To this solution, 180 parts by mass of conductive particles 1 (titanium oxide particles 500SAS (manufactured by Teika Corporation)) was added. Then, using a bead mill, it was dispersed with a mill residence time of 5 hours (1000 rpm). After allowing this solution to stand for a whole day and night, it was filtered to obtain a coating solution for forming the intermediate layer. Filtration was performed under a pressure of 50 kPa using a rigid mesh filter (manufactured by Nippon Pall Corporation) with a nominal filtration accuracy of 5 μm as the filter. The coating solution for forming the intermediate layer thus obtained was applied to the outer peripheral surface of the washed conductive support by dip coating, and dried at 120°C for 30 minutes to form an intermediate layer with a dry film thickness of 2 μm.

[0147] (2) Formation of the charge - generating layer As materials for the charge - generating layer, the following components were prepared. (i) Charge - generating substance (a mixed crystal of titanyl phthalocyanine having distinct peaks at 8.3°, 24.7°, 25.1°, and 26.5° in the Cu - Kα characteristic X - ray diffraction spectrum measurement and a 1:1 adduct of (2R,3R) - 2,3 - butanediol and un - added titanyl phthalocyanine) 24 parts by mass (ii) Polyvinyl butyral resin (Esrec BL - 1, manufactured by Sekisui Chemical Co., Ltd., "Esrec" is a registered trademark of the company) 12 parts by mass (iii) A mixed solution of 3 - methyl - 2 - butanone and cyclohexanone (volume ratio: 4 / 1) 400 parts by mass The materials (i) to (iii) above were mixed and dispersed using a circulation - type ultrasonic homogenizer RUS - 600TCVP (manufactured by Nippon Seiki Co., Ltd.) at 19.5 kHz and 600 W with a circulation flow rate of 40 L / H for 0.5 hours to prepare a coating solution for the charge - generating layer. The coating solution for the charge - generating layer was applied to the surface of the above - mentioned intermediate layer by dip coating and dried to form a charge - generating layer with a film thickness of 0.3 μm on the intermediate layer.

[0148] (3) Formation of the charge - transport layer As materials for the charge transport layer, the following components were prepared. (a) 60 parts by mass of a charge transport substance precursor (Compound 1) represented by the following general formula [Chemical formula] (b) 100 parts by mass of a polycarbonate resin (Z300, manufactured by Mitsubishi Gas Chemical Company) (c) 4 parts by mass of an antioxidant (IRGANOX 1010, manufactured by BASF, IRGANOX is a registered trademark of the company) A coating solution for the charge transport layer was prepared by mixing and dissolving the materials (a) to (c) above. The coating solution for the charge transport layer was applied to the surface of the charge generation layer by the dip coating method and dried at 120 °C for 70 minutes to polymerize the charge transport substance precursor. As a result, a charge transport layer with a thickness of 24 μm containing the charge transport substance precursor having the structure represented by the above general formula (1) was obtained.

[0149] 1-2. Preparation of the electrophotographic photoreceptor 2 (electrophotographic photoreceptor of Example 2) An electrophotographic photoreceptor 2 was prepared in the same manner as the electrophotographic photoreceptor 1, except that Compound 1, which is a charge transport substance precursor, was changed to the following Compound 2. Also in this case, a charge transport layer containing the charge transport substance having the structure represented by the above general formula (1) was obtained. [Chemical formula]

[0150] 1-3. Preparation of the electrophotographic photoreceptor 3 (electrophotographic photoreceptor of Comparative Example 1) An electrophotographic photoreceptor 3 was prepared in the same manner as the electrophotographic photoreceptor 1, except that Compound 1, which is a charge transport substance precursor, was changed to the following Compound 3. In this case, the charge transport layer does not contain the charge transport substance having the structure represented by the above general formula (1). [Chemical formula]

[0151] 2. Preparation of toner 2-1. Preparation of toner mother particles (1) Preparation of Amorphous Resin Particle Dispersion (First-stage Polymerization) In a reaction vessel equipped with a stirring device, a temperature sensor, a cooling pipe, and a nitrogen introduction device, a surfactant solution was prepared by dissolving 8 parts by mass of sodium dodecyl sulfate in 3000 parts by mass of ion-exchanged water. While stirring at a stirring speed of 230 rpm under a nitrogen stream, the internal temperature was raised to 80°C. After the temperature rise, a solution prepared by dissolving 10 parts by mass of potassium persulfate (KPS) in 200 parts by mass of ion-exchanged water was added to the above surfactant solution. After adjusting the liquid temperature to 80°C again, a polymerizable monomer mixture containing the following compounds was added dropwise over 1 hour. Styrene 480 parts by mass n-Butyl acrylate 250 parts by mass Methacrylic acid 68 parts by mass n-Octyl-3-mercaptopropionate 16 parts by mass After the dropwise addition of the above polymerizable monomer mixture, the system was heated and stirred at 80°C for 2 hours to carry out polymerization (first-stage polymerization), and a resin particle dispersion [1H] containing resin particles (1h) was prepared.

[0152] (Second-stage Polymerization) In a flask equipped with a stirring device, the following compounds were added and heated to 90°C to dissolve, and the following mixed solution containing a polymerizable monomer and a release agent was prepared. Styrene 245 parts by mass n-Butyl acrylate 120 parts by mass n-Octyl-3-mercaptopropionate 1.5 parts by mass Paraffin wax HNP-11 (manufactured by Nippon Seiro Co., Ltd.) 67 parts by mass

[0153] On the one hand, a surfactant solution prepared by dissolving 7 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 800 parts by mass of ion-exchanged water was heated to 98°C. To this surfactant solution, a resin particle dispersion (1H) in an amount of 260 parts by mass in terms of solid content of the above resin particles (1h) and a mixed solution containing the above polymerizable monomer and a release agent were added. After their addition, a mechanical disperser Clear Mix (manufactured by M. Technique Co., Ltd.) having a circulation path was used to perform a mixing and dispersing treatment for 1 hour to prepare a dispersion containing emulsified particles.

[0154] Next, a solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 82°C for 1 hour to carry out polymerization (second-stage polymerization) to prepare a resin particle dispersion (1HM) containing resin particles (1hm).

[0155] (Third-stage polymerization) To the resin particle dispersion (1HM) prepared above, an initiator solution prepared by dissolving 11 parts by mass of potassium persulfate in 400 parts by mass of ion-exchanged water was added, and the liquid temperature was adjusted to 80°C. Then, a polymerizable monomer mixture containing the following compounds was added dropwise over 1 hour. Styrene 435 parts by mass n-Butyl acrylate 130 parts by mass Methacrylic acid 33 parts by mass n-Octyl 3-mercaptopropionate 8 parts by mass

[0156] After completion of the dropwise addition of the above polymerizable monomer mixture, polymerization (third-stage polymerization) was carried out by heating and stirring for 2 hours, and then cooled to 28°C to prepare a resin particle dispersion containing resin particles. When the particle diameter of the resin particles contained in the resin particle dispersion was measured using an electrophoretic light scattering photometer ELS-800 (manufactured by Otsuka Electronics Co., Ltd.), it was 150 nm in terms of volume-based median diameter. Also, when the glass transition temperature was measured by a known method, it was 45°C. The weight average molecular weight of the resin constituting the resin particles was 32,000.

[0157] (2) Preparation of crystalline polyester resin fine particle dispersion Into a heated and dried three-necked flask, 355.8 parts by mass of dodecanedioic acid (1,10-decanedicarboxylic acid) as a polycarboxylic acid monomer, 254.3 parts by mass of 1,9-nonanediol as a polyhydric alcohol monomer, and 3.21 parts by mass of tin octylate as a catalyst were added. After removing the air in the container by a vacuum operation, it was replaced with nitrogen gas to create an inert atmosphere, and reflux treatment was performed at 180 °C for 5 hours with mechanical stirring. While maintaining the inert atmosphere, the temperature was gradually increased, and stirring was carried out at 200 °C for 3 hours to obtain a viscous liquid product. Further, while air-cooling, the molecular weight of this product was measured by GPC, and when the weight average molecular weight (Mw) reached 15000, the vacuum was released to stop the polycondensation reaction, and a crystalline polyester resin was obtained. The obtained crystalline polyester resin had a melting point of 69 °C.

[0158] Methyl ethyl ketone and isopropyl alcohol were added to a reaction vessel equipped with an anchor blade for imparting stirring power. Further, the above-mentioned crystalline polyester resin coarsely pulverized with a hammer mill was gradually added and stirred to be completely dissolved to obtain a polyester resin solution that became an oil phase. A dilute aqueous ammonia solution was dropped by a certain amount into the stirred oil phase, and then this oil phase was dropped into ion-exchanged water for phase inversion emulsification, and then the solvent was removed while reducing the pressure with an evaporator. Crystalline polyester resin fine particles were dispersed in the reaction system, and ion-exchanged water was added to the dispersion to adjust the solid content to 20% by mass to prepare a crystalline polyester resin fine particle dispersion.

[0159] When the volume-based median diameter of the crystalline polyester resin fine particles in the dispersion was measured using a particle size distribution measuring instrument "Nanotrack Wave" (manufactured by Microtrac Bel), it was 173 nm.

[0160] (3) Preparation of amorphous polyester resin fine particle dispersion A reaction vessel equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor, and a rectification column was charged with 139.5 parts by mass of terephthalic acid and 15.5 parts by mass of isophthalic acid as polycarboxylic acid monomers, and 290.4 parts by mass of a 2-mole adduct of 2,2-bis(4-hydroxyphenyl)propane and propylene oxide (molecular weight = 460) and 60.2 parts by mass of a 2-mole adduct of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide (molecular weight 404) as polyhydric alcohol monomers.

[0161] The temperature of the reaction system was raised to 190 °C over 1 hour, and after confirming that the inside of the reaction system was uniformly stirred, 3.21 parts by mass of tin octylate was added as a catalyst. While distilling off the generated water, the temperature of the reaction system was raised from the same temperature to 240 °C over 6 hours, and the dehydration condensation reaction was continuously carried out for 6 hours while maintaining the temperature at 240 °C to obtain an amorphous polyester resin. The obtained amorphous polyester resin had a weight average molecular weight (Mw) of 15,000.

[0162] For the obtained amorphous polyester resin, a dispersion of amorphous polyester resin fine particles with a solid content of 20% by mass was prepared by performing the same operations as in the preparation of the crystalline polyester resin fine particle dispersion. When the volume-based median diameter of the amorphous polyester resin fine particles in the dispersion was measured using a particle size distribution measuring instrument "Nanotrack Wave" (manufactured by Microtrac Bell), it was 216 nm.

[0163] (4) Preparation of colorant particle dispersion While stirring a solution prepared by dissolving 90 parts by mass of sodium dodecyl sulfate in 1600 parts by mass of ion-exchanged water, 420 parts by mass of aluminum pigment 2173EA (manufactured by Toyo Aluminum Co., flatness 15, major axis 30 μm, thickness 2 μm) was gradually added to the solution. Next, dispersion treatment was performed using a stirring device ClearMix (manufactured by M Technique Co., Ltd.) to obtain a colorant particle dispersion.

[0164] (5) Preparation of toner mother particles The following compounds were charged into a reaction vessel equipped with a stirring device, a temperature sensor, a cooling pipe, and a nitrogen introduction device. 270 parts by mass (in terms of solid content) of a styrene-acrylic resin particle dispersion 60 parts by mass (in terms of solid content) of a crystalline polyester resin fine particle dispersion 270 parts by mass (in terms of solid content) of an amorphous polyester resin fine particle dispersion 1400 parts by mass of ion-exchanged water 180 parts by mass (in terms of solid content) of a colorant particle dispersion Next, a solution prepared by dissolving 3 parts by mass of polyoxyethylene-2-sodium dodecyl sulfate in 120 parts by mass of ion-exchanged water was added to the above reaction vessel. After adjusting the liquid temperature to 30°C, a 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 10.

[0165] Subsequently, an aqueous solution prepared by dissolving 35 parts by mass of magnesium chloride hexahydrate in 35 parts by mass of ion-exchanged water was added dropwise at 30°C over 10 minutes while stirring, and held for 3 minutes, and then the temperature was raised. The temperature was raised to 90°C over 60 minutes, and the aggregation and fusion of the above particles were carried out while maintaining the temperature at 90°C. In this state, the particle size of the particles growing in the reaction vessel was measured using a Multisizer 3 (manufactured by Beckman Coulter). When the volume-based median diameter reached 6.5 μm, an aqueous solution prepared by dissolving 150 parts by mass of sodium chloride in 600 parts by mass of ion-exchanged water was added to stop the growth of the particles. Further, as an aging treatment, the liquid temperature was raised to 98°C and heated and stirred to promote the fusion of the particles. Thereafter, the liquid temperature was cooled to 30°C, the pH of the liquid was adjusted to 2 using hydrochloric acid, and the stirring was stopped to prepare a toner mother particle dispersion.

[0166] The toner base particle dispersion was subjected to solid-liquid separation using a basket centrifuge MARKIII, model number 60×40 (manufactured by Matsumoto Machinery Co., Ltd.) to form a wet cake of toner base particles. The wet cake was washed with ion-exchanged water at 45 °C using a basket centrifuge until the electrical conductivity of the filtrate reached 5 μS / cm, and then transferred to a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.) for drying until the moisture content reached 0.5 mass% to produce toner base particles of the bright toner.

[0167] 2-2. Production of external additive (1) Production of lanthanum-doped strontium titanate particles After subjecting metatitanic acid obtained by the sulfuric acid method to iron removal and bleaching treatment, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, and desulfurization treatment was performed. Then, it was neutralized to pH 5.8 with hydrochloric acid and subjected to filtration and washing with water. Water was added to the washed cake to make a slurry with a TiO 2 concentration of 1.85 mol / L, and then hydrochloric acid was added to adjust the pH to 1.0 for peptization treatment. 0.625 mol of this metatitanic acid was taken as TiO 2 and put into a 3 L reaction vessel. An aqueous strontium chloride solution and an aqueous lanthanum chloride solution were added to the reaction vessel so that the molar ratio of Sr 2+ :La 3+ :Ti 4+ was 1.00:0.18:1.00, and a total of 0.719 mol was added. Then, the TiO 2 concentration was adjusted to 0.313 mol / L. Next, it was heated to 90 °C while stirring and mixing, and then 296 mL of 5N aqueous sodium hydroxide solution was added over 26 hours. After that, stirring was continued at 95 °C for 1 hour to complete the reaction.

[0168] The reaction slurry was cooled to 50 °C, hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 1 hour. The resulting precipitate was washed by decantation, hydrochloric acid was added to the slurry containing the precipitate to adjust the pH to 6.5, 9% by mass of isobutyltrimethoxysilane was added based on the solid content, and stirring was continued for 1 hour. Subsequently, filtration and washing were performed, and the obtained cake was dried in air at 120 °C for 8 hours to obtain lanthanum-doped strontium titanate particles. When the obtained particles were observed with an electron microscope, they were particles with a primary particle size of 26 to 33 nm. The number-average primary particle size calculated based on the mass using the electron micrograph was 30 nm. Also, the average circularity was 0.85.

[0169] (2) Method for producing lanthanum-doped calcium titanate particles Using an aqueous calcium chloride solution instead of the aqueous strontium chloride solution, Ca 2+ :La 3+ :Ti 4+ Lanthanum-doped calcium titanate particles were obtained in the same manner as the method for producing lanthanum-doped strontium titanate particles, except that the addition was made so that the molar ratio of was 1.00:0.18:1.00. When the obtained particles were observed with an electron microscope, they were particles with a primary particle size of 26 to 33 nm. The number-average primary particle size calculated based on the mass using the electron micrograph was 30 nm. Also, the average circularity was 0.85.

[0170] (3) Production of lanthanum-doped magnesium titanate particles Using an aqueous magnesium chloride solution instead of the aqueous strontium chloride solution, Mg 2+ :La 3+ :Ti 4+ Lanthanum-doped magnesium titanate particles were obtained in the same manner as the production method of lanthanum-doped strontium titanate, except that the addition was made so that the molar ratio of was 1.00:0.18:1.00. When the obtained particles were observed with an electron microscope, they were particles with a primary particle size of 25 to 34 nm. The number-average primary particle size calculated based on the mass using the electron micrograph was 30 nm. Also, the average circularity was 0.85.

[0171] (4) Production of Strontium Titanate Particles Sr 2+ :La 3+ :Ti 4+ Strontium titanate particles were obtained in the same manner as the production method of lanthanum-doped strontium titanate particles, except that the molar ratio of Sr 2+ :La 3+ :Ti 4+ was changed to 1.00:0:1.00. When the obtained particles were observed with an electron microscope, they were particles with a primary particle diameter of 26 to 33 nm. The number average primary particle diameter calculated on a mass basis using an electron micrograph was 30 nm. Also, the average circularity was 0.75.

[0172] 2-3. Preparation of Toner (1) Preparation of Toner 1 (used in Examples 1 and 2, and Comparative Example 1) Toner mother particles and lanthanum-doped strontium titanate were added to a Henschel mixer model FM20C / I (manufactured by Nippon Coke Industry Co., Ltd.) so that the content of the lanthanum-doped strontium titanate compound with respect to the total amount of the toner was 0.5% by mass and the content of hydrophobic silica (HMDS-treated, degree of hydrophobicity 72%, number average primary particle diameter 20 nm) was 0.5% by mass. Next, the rotation speed was set so that the tip peripheral speed of the blades was 40 m / s, and the external addition treatment was performed by stirring for 15 minutes to prepare Toner 1. The temperature during the external addition treatment was set to be within the range of 39 to 41°C. Specifically, when the temperature inside the above Henschel mixer reached 41°C, cooling water was flowed through the outer bath of the Henschel mixer at a flow rate of 5 L / min, and when it reached 39°C, cooling water was flowed through the outer bath of the Henschel mixer at a flow rate of 1 L / min to control the temperature inside the Henschel mixer.

[0173] (2) Preparation of Toner 2 (used in Example 3) A toner was prepared in the same manner as Toner 1, except that lanthanum-doped strontium titanate was not used.

[0174] (3) Preparation of Toner 3 (used in Example 4) A toner was prepared in the same manner as Toner 1, except that calcium lanthanum-doped titanate was used instead of strontium lanthanum-doped titanate.

[0175] (4) Preparation of Toner 4 (used in Example 5) A toner was prepared in the same manner as Toner 1, except that magnesium lanthanum-doped titanate was used instead of strontium lanthanum-doped titanate.

[0176] (5) Preparation of Toner 5 (used in Example 6) A toner was prepared in the same manner as Toner 1, except that the particle size of strontium lanthanum-doped titanate was changed.

[0177] (6) Preparation of Toner 6 (used in Example 7) A toner was prepared in the same manner as Toner 1, except that the particle size of strontium lanthanum-doped titanate was changed.

[0178] (7) Preparation of Toner 7 (used in Example 8) A toner was prepared in the same manner as Toner 1, except that the addition amount of strontium lanthanum-doped titanate was changed to the value shown in Table 1.

[0179] (8) Preparation of Toner 8 (used in Example 8) A toner was prepared in the same manner as Toner 1, except that the addition amount of strontium lanthanum-doped titanate was changed to the value shown in Table 1.

[0180] (9) Preparation of Toner 9 (used in Example 10) A toner was prepared in the same manner as Toner 1, except that strontium titanate was used instead of strontium lanthanum-doped titanate.

[0181] (10) Preparation of Toner 10 (used in Example 11) A toner was prepared in the same manner as Toner 1, except that the colorant in the toner base particles was changed to a gold pigment (manufactured by Nippon Sheet Glass Co., Ltd., Metashine, Titania Coat Standard Type, major axis 20 μm, thickness 1 μm).

[0182] (11) Preparation of Toner 11 (used in Example 12) The toner was prepared in the same manner as Toner 1, except that the colorant in the toner base particles was changed to a pearl pigment (major axis: 40 μm, thickness: 0.5 μm).

[0183] 3. Image Formation and Evaluation 3-1. Example 1 The above-described electrophotographic photoreceptor 1 was installed in a modified AccurioPress C12000 (manufactured by Konica Minolta). Then, the above Toner 1 was filled into the apparatus. And the photoreceptor filming resistance, photoreceptor abrasion resistance, and uniformity of metallic luster were evaluated by the following method.

[0184] (Photoreceptor Filming Resistance) Using the above apparatus, a printed image with a coverage of 5% was continuously printed 100,000 sheets in an environment of 33°C and 80% RH (relative humidity). Then, a black image with a coverage of 20% was continuously printed 20,000 sheets. Then, an A3 solid black image was created with toner, and the state of white spots due to photoreceptor filming was evaluated based on the following evaluation criteria. △ or above is within the range where there are no practical problems. ◎: The number of filmings on the photoreceptor is 0 to 5, and the number of white spots on the image is 0 to 2 ○: The number of filmings on the photoreceptor is 6 to 10, and the number of white spots on the image is 3 to 6 △: The number of filmings on the photoreceptor is 11 to 30, and the number of white spots on the image is 7 to 10 ×: The number of filmings on the photoreceptor is 31 or more, and the number of white spots on the image is 11 or more

[0185] (Photoreceptor Abrasion Resistance) Using the above device, printing was performed 30,000 times on a character chart with a toner printing rate of 5% in the examples and comparative examples, the wear amount on the surface of the electrophotographic photoreceptor was measured, and evaluation was carried out according to the following criteria. The initial film thickness (μm) of the laminate film (laminate film composed of an intermediate layer, a charge generation layer, and a charge transport layer) of the photoreceptor before starting the image formation test was measured, and also the film thickness (μm) after the image formation test was measured, and the difference ΔT (μm) in the film thickness of the laminate film of the photoreceptor before and after the image formation test was calculated. The film thickness of the laminate film of the photoreceptor was measured at 10 random locations in the uniform film thickness portion (at least 3 cm at both ends were excluded because the film thickness tends to be non-uniform at both ends of the photoreceptor), and the average value was taken as the film thickness of the laminate film of the photoreceptor.

[0186] For the film thickness measuring instrument, an eddy current type film thickness measuring instrument "EDDY560C" (manufactured by Helmuth Fischer) was used. The difference ΔT (μm) in the film thickness of the laminate film of the photoreceptor before and after the image formation test was converted per 100 krot (100,000 rotations) of the photoreceptor to obtain the α value (μm / 100,000 rotations), and this was taken as the wear amount of the photoreceptor. Using the obtained α value, the abrasion resistance was evaluated according to the following criteria. Δ or more is within the range where there are no practical problems. ◎: α value ≤ 0.1 (very excellent) ○: 0.1 < α value ≤ 0.2 (excellent) △: 0.2 < α value ≤ 0.3 (no practical problems) ×: 0.3 < α value (there are practical problems)

[0187] (Metallic luster uniformity) OK top coat 128 g / m 2 A solid patch with a length of 3 cm and a width of 5 cm was formed, and the uniformity of the metallic luster was evaluated visually according to the following criteria. Δ or more is within the range where there are no practical problems. ◎: The metallic luster is in a very uniform state 〇: The metallic luster is in a uniform state △: There is a slight non-uniform part in the metallic luster ×: The metallic luster is clearly non-uniform

[0188] 3-2. Example 2 An image was formed and evaluated in the same manner as in Example 1, except that the electrophotographic photoreceptor 2 was used instead of the electrophotographic photoreceptor 1.

[0189] 3-3. Examples 3 to 12 An image was formed and evaluated in the same manner as in Example 1, except that the toner was changed as shown in Table 1.

[0190] 3-4. Comparative Example 1 An image was formed and evaluated in the same manner as in Example 1, except that the electrophotographic photoreceptor 3 was used instead of the electrophotographic photoreceptor 1.

[0191]

Table 1

[0192] As shown in Table 1 above, when a photosensitive layer (photoreceptor) containing a specific charge transport material was combined with a toner containing a fluorescent pigment, filming was less likely to occur on the photoreceptor, and furthermore, the abrasion resistance was also good (Examples 1 to 12). It is considered that while the hardness of the charge transport layer was moderately hard, it was possible to polish with the fluorescent toner. Also, according to the said image forming method, the uniformity of the metallic luster feeling also became good. This is presumably because the charge transport property of the charge transport layer was good.

[0193] On the other hand, when the photosensitive layer did not contain a compound having a specific structure, the abrasion resistance was not sufficient, and furthermore, the metallic luster uniformity was likely to be low (Comparative Example 1).

Industrial Applicability

[0194] According to the image forming method of the present invention, it is possible to form a highly artistic image with a fluorescent toner without causing filming or cleaning defects on the electrophotographic photoreceptor. Therefore, according to the present invention, it is expected to contribute to the further spread of electrophotographic image forming methods.

Explanation of Signs

[0195] 1 Image forming apparatus 3 Photosensitive layer 10 Conductive support 11 Charge generation layer 12 Charge transport layer 30 Image processing unit 40 Image forming unit 41Y, 41M, 41C, 41K, 41L Image forming units 42 Intermediate transfer unit 43 Secondary transfer unit 50 Paper conveyance unit 51 Paper feeding unit 51a, 51b, 51c Paper feed tray units 52 Paper discharge unit 52a Paper discharge roller 53 Conveyance path unit 53a Registration roller pair 60 Fixing means 62 Fixing roller 63 Heating belt 64 Pressing roller 110 Image reading unit 111 Paper feeding device 112 Scanner 112a CCD sensor 411 Exposure means 412 Development means 413 Photoconductor 414 Charging means 415 Drum cleaning device 421 Intermediate transfer belt 422 Primary transfer roller 423, 431 Support rollers 423A Backup roller 426 Belt cleaning device 431A Secondary transfer roller 432 Secondary transfer belt D Original document

Claims

1. A step of preparing an image forming apparatus having an electrophotographic photoreceptor with a photosensitive layer; A step of forming an electrostatic latent image on the surface of the photosensitive layer; A step of developing the electrostatic latent image with an electrostatic charge image developing toner containing a bright pigment having a flatness exceeding 1.4 to form an image; which comprises; The photosensitive layer contains a charge transport material having a structure represented by the following general formula (1); 【Chemical 1】 (In general formula (1), R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, k and l each independently represent an integer of 1 to 5, X represents a single bond or an alkyl chain, and Y represents a structure after a reactive group selected from the group consisting of an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, a vinyl ether group, and derivatives thereof reacts and polymerizes.) An image forming method.

2. X in the general formula (1) is a group represented by the following general formula (2); [Chemical Formula 2] (In general formula (2), m represents an integer from 0 to 5) Y in the general formula (1) is a structure derived from a group represented by the following general formula (3) or general formula (4); 【Chemical Formula 3】 The image forming method according to claim 1.

3. The electrostatic charge image developing toner further contains a lanthanum-doped titanate compound; The image forming method according to claim 1 or 2.

4. The lanthanum-doped titanate compound is at least one compound selected from the group consisting of lanthanum-doped strontium titanate, lanthanum-doped calcium titanate, and lanthanum-doped barium titanate; The image forming method according to claim 3.

5. The number average primary particle diameter of the lanthanum-doped titanate compound is 10 to 100 nm; The image forming method according to claim 3 or 4.

6. The content of the lanthanum-doped titanate compound is 0.1 to 1.0% by mass based on the total amount of the electrostatic charge image developing toner; The image forming method according to any one of claims 3 to 5.

7. An electrophotographic photoreceptor with a photosensitive layer; Charging means for charging the surface of the electrophotographic photoreceptor; Exposing means for exposing the charged surface of the electrophotographic photoreceptor to form an electrostatic latent image; Developing means for developing the electrostatic latent image with an electrostatic charge image developing toner to form a visible image; Transferring means for transferring the visible image to a recording medium; Fixing means for fixing the transferred image on the recording medium; An image forming apparatus comprising; The photosensitive layer contains a charge transport material having a structure represented by the following general formula (1); 【Chemical Formula 4】 (In general formula (1), R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, k and l each independently represent an integer of 1 to 5, X represents a single bond or an alkyl chain, and Y represents a structure after a reactive group selected from the group consisting of an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, a vinyl ether group, and derivatives thereof reacts and polymerizes.) The electrostatic charge image developing toner contains a bright pigment having a flatness exceeding 1.4; An image forming apparatus.

Images